1. Field
The described technology relates generally to an organic material depositing device and depositing method.
2. Description of the Related Art
An organic light emitting diode (OLED) display is a flat display device that has a self emissive characteristic and does not require a separate light source, so that it can be made light in weight and thin. An OLED display exhibits quality characteristics such as low power consumption, high luminance, and fast (or high) response speed, and as such, the OLED display receives much attention as a next-generation display device.
In general, an OLED display includes an organic light emitting element that has an anode, an organic emission layer, and a cathode. Holes and electrons are injected from the anode and the cathode, respectively, to form excitons, and the excitons transition to a ground state, thereby causing the organic light emitting diode to emit light.
An organic emission layer can be formed with an organic thin film, and methods for forming the organic thin film on the substrate of the organic light emitting diode (OLED) display include the vacuum depositing method and the wet coating method. As a general method to form an organic thin film, the vacuum deposition method is used to form an organic thin film in a vapor deposition apparatus that includes an organic material evaporation source having a crucible. The organic thin film is formed by inserting a vapor deposition material in the crucible and depositing the vapor deposition material by heating the crucible to a predetermined temperature.
According to the vacuum deposition method, a mask is used to form an organic thin film pattern. The mask includes shields having a predetermined thickness, and openings for depositing a deposition material on the substrate are formed between the shields of the mask. In this instance, the deposition source moves linearly in the vacuum to output deposition material particles, and part of the deposition material particles are blocked (or intercepted) at the edge of the mask shield having a predetermined thickness, and are not deposited on the substrate. Because of the blocking influence by the shield, a shadow effect occurs, resulting in a non-uniform thickness of the organic thin film in the pixel on the substrate. The non-uniformity corresponds to the openings in the mask, and the thickness of the organic thin film at the edge of the pixel may be reduced.
When the thickness of the organic thin film deposited in the organic light emitting element is not uniformly formed, the organic light emitting element may emit light abnormally and an entire area of the organic light emitting diode (OLED) display may not provide uniform light emission.
It is not easy to change the deposition source in order to reduce or prevent the shadow effect. Further, when a taper angle of the mask shield is reduced by modifying (or improving) the form of the mask, a gap between openings of the mask may increase and a gap between the pixels may increase, such that a high-resolution organic light emitting diode (OLED) display may not be generated.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology. Therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.